You can search for this bug and it seems like it may be related to ecryptfs and is many years old.
The symptoms are that you return to the computer and the screensaver was active or the screen was asleep/black and it doesn't seem to come back. But you check by SSH the computer is running fine and are frustrated you'll lose your running programs and have to reboot.
There is a simple solution:
Ctrl + Alt + F1
Ctrl +Alt + F8
Ba........
Here is the only solution Ifound that works in Firefox:
*Note you could basically just copy all of the commands in bold (the rest just shows the output)
Install sqlite3
sqlite3 places.sqlite
sqlite> .clone places.sqlite-fixed
moz_places... done
moz_historyvisits... done
moz_inputhistory..........
Jun 1 15:45:42 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory[1882]: project_data:INFO Missing folder chosen by user:
Jun 1 15:45:42 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory[1882]: project_data:INFO Removed missing file: MAH02949.MP4
Jun 1 15:45:57 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory[1882]: ui_util:WARNING Icon theme media-playback-start not found. Will use backup........